露天爆破震动诱发地下洞室顶板失稳的非线性机理分析

开挖爆破是诱发工程岩体失稳的重要因素.根据露天与地下联合开采特点,将地下洞室顶板简化为水平简支梁,基于非线性理论分析方法建立了露天爆破震动扰动诱发地下洞室顶板失稳的突变理论模型,导出了其失稳判据条件和临界安全厚度,探讨了爆破震动幅值、主频、围岩特性等主要因素对地下洞室顶板临界安全厚度的影响.以甘肃厂坝铅锌矿群采空区顶板安全厚度分析为例,计算得到了露天与地下采场之间顶板的临界安全厚度.研究结果表明:露天爆破扰动诱发地下洞室顶板失稳过程具有非线性和不连续性特征,顶板临界安全厚度不仅取决于岩体工程特性,而且与爆破震动幅值、主频等多重因素有关,这与实际情况是吻合的.

NONLINEAR MECHANISM ANALYSIS OF UNDERGROUND CHAMBER ROOF INSTABILITY INDUCED BY OPEN BLASTING VIBRATION

The blasting excavation is an important influencong factor for the instability of engineering rock mass.In view of the characteristics of combined mining for open-pit and underground,catastrophe theory models of the underground chamber roof instability induced by open blasting disturbance are built by taking the underground chamber roof as a horizontal simply supported beam based on the non-linear theory.The instability criteria and the critical safe thickness of the underground chamber roof are derived according to the catastrophe theory models.At the same time,the important influencing factors for the critical safe thickness of the underground chamber roof,such as the amplitude and the key frequency of the blasting vibration,and the characteristics of the surrounding rock are discussed.The critical safe thickness of the roof between the open-pit and underground stopes is obtained by a safe thickness analysis of Changba Pb-Zn deposit group mined-out area roofs in Gansu province as an example.It is shown that the dynamic instability of the underground chamber roof is obviously nonlinear and discontinuous,while the critical safe thickness of the underground chambers roof not only depends on engineering geological characteristics of the roof,but also on other multiple factors,for example,the amplitude and the key frequency of the blasting disturbance,as is consistent with the actual situation.